The present invention relates apparatus for displaying drawings. More specifically, this invention relates to an apparatus for displaying drawings which makes use of a rewritable medium, preferably an electrophoretic medium.
The present invention also relates to displays incorporating touch screens.
The term drawings is used herein to cover, inter alia, construction drawings, blueprints, architectural drawings, maps, plans, and similar types of technical drawings which may be required, for example, for the assembly, repair and maintenance of machinery.
Electro-optic displays comprise a layer of electro-optic material, a term which is used herein in its conventional meaning in the art to refer to a material having first and second display states differing in at least one optical property, the material being changed from its first to its second display state by application of an electric field to the material. The optical property is typically color perceptible to the human eye, but may be another optical property, such as optical transmission, reflectance, luminescence or, in the case of displays intended for machine reading, pseudo-color in the sense of a change in reflectance of electromagnetic wavelengths outside the visible range. The electro-optic material may be a particle-based electrophoretic material comprising at least one type of electrically charged particle capable of moving through a suspending fluid upon application of an electric field, and such an electrophoretic material may or may not be encapsulated; see, for example, U.S. Pat. Nos. 5,930,026; 5,961,804; 6,017,584; 6,067,185; 6,118,426; 6,120,588; 6,120,839; 6,124,851; 6,130,773; 6,130,774; 6,172,798; 6,1 77,921; 6,232,950; 6,241,921; 6,249,271; 6,252,564; 6,262,706; 6,262,833; 6,300,932; 6,312,304; 6,312,971; 6,323,989; and 6,327,072; U.S. Patent Application Publication No. 2001-0045934; and International Applications Publication Nos. WO 97/04398; WO 98/03896; WO 98/19208; WO 98/41898; WO 98/41899; WO 99/10767; WO 99/10768; WO 99/10769; WO 99/47970; WO 99/53371; WO 99/53373; WO 99/56171; WO 99/59101; WO 99/67678; WO 00/03349; WO 00/03291; WO 00/05704; WO 00/20921; WO 00/20922; WO 00/20923; WO 00/26761; WO 00/36465; WO 00/36560; WO 00/36666; WO 00/38000; WO 00/38001; WO 00/59625; WO 00/60410; WO 00/67110; WO 00/67327 WO 01/02899; WO 01/07691; WO 01/08241; WO 01/08242; WO 01/17029; WO 01/17040; WO 01/17041; WO 01/80287 and WO 02/07216. The entire disclosures of all these patents and published applications, all of which are in the name of, or assigned to, the Massachusetts Institute of Technology (MIT) or E Ink Corporation, are herein incorporated by reference. Alternatively, the electro-optic material may be of the rotating bichromal member type as described, for example, in U.S. Pat. Nos. 5,808,783; 5,777,782; 5,760,761; 6,054,071 6,055,091; 6,097,531; 6,128,124; 6,137,467; and 6,147,791 (although this type of display is often referred to as a “rotating bichromal ball” display, the tern “rotating bichromal member” is preferred as more accurate since in some of the patents mentioned above the rotating members are not spherical). The electro-optic medium could also be an electrochromic medium, for example an electrochromic medium in the form of a nanochromic film comprising an electrode formed at least in part from a semi-conducting metal oxide and a plurality of dye molecules capable of reversible color change attached to the electrode; see, for example O'Regan, B., et al., Nature 1991, 353, 737. Nanochromic films of this type are also described, for example, in International Applications Publication Nos. WO 98/35267 and WO 01/27690; the entire contents of these two applications are herein incorporated by reference. Other types of electro-optic materials, for example, liquid crystals, especially polymer-dispersed liquid crystals, may also be used in such displays.
Some electro-optic displays can have attributes of good brightness and contrast, wide viewing angles, state bistability, and low power consumption when compared with liquid crystal displays. (The terms bistable and bistability are used herein in their conventional meaning in the art to refer to displays comprising display elements having first and second display states differing in at least one optical property, and such that after any given element has been driven, by means of an addressing pulse of finite duration, to assume either its first or second display state, after the addressing pulse has terminated, that state will persist for at least several times, for example at least four times, the minimum duration of the addressing pulse required to change the state of the display element.)
An encapsulated, electrophoretic display typically does not suffer from the clustering and settling failure mode of traditional electrophoretic devices and provides further advantages, such as the ability to print or coat the display on a wide variety of flexible and rigid substrates. (Use of the word printing is intended to include all forms of printing and coating, including, but without limitation: pre-metered coatings such as patch die coating, slot or extrusion coating, slide or cascade coating, curtain coating; roll coating such as knife over roll coating, forward and reverse roll coating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; silk screen printing processes; electrostatic printing processes; thermal printing processes; ink jet printing processes; and other similar techniques.) Thus, the resulting display can be flexible. Further, because the display medium can be printed (using a variety of methods), the display itself can be made inexpensively.
It has now been realized that the properties of many electro-optic media, and especially the aforementioned encapsulated electrophoretic media, in particular their rewritable nature and their bistability, render such media especially adapted for solving certain problems associated with display of drawings under conditions often experienced in industry (including the construction industry). Accordingly, in one aspect this invention relates to apparatus useful for display of drawings and adapted to take advantage of the properties of such media.
Architects, builders and engineers employed in the construction industry working on large projects may require frequent access to hundreds, if not thousands, of drawings, and it is impracticable for them to carry a complete set of such drawings around with them. Although electronic storage of the necessary drawings would appear to be the solution, the display devices conventionally used with electronic storage are not well adapted for either the type of drawings involved or the environment in which they have to be used. Computer monitors based on cathode ray tubes are, of course, too large and heavy, and require too much power, to be useful to someone moving around a construction site. Liquid crystal displays of the type used in portable computers are sufficiently light in weight and have sufficiently low power consumption for such purposes, but are fragile and difficult to read in sunlight. Furthermore, the maximum size of such displays is limited to about 15 inches diagonal, whereas construction drawings need to be much larger (typically about 24 by 36 inches) in order to show to scale details of a large building or device, and it is difficult to work with such drawings without seeing the whole drawing at once. Finally, construction sites present severe environmental hazards to portable computers, which may be damaged by rain, mud, blowing dust or excessive heat or cold. Similar problems are encountered by others needing access to large numbers of complex drawings, for example aircraft maintenance technicians.
The aforementioned media can readily be produced in the form of large, lightweight, tough rewritable sheets well adapted for display of construction and similar drawings, and such sheets can be incorporated into several types of storage devices which are less susceptible to the environmental hazards of construction sites and similar locations that are conventional portable computers. It is to such storage devices that the present invention relates.